Fixed width integer types (since C99)

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[edit] Types

Defined in header <stdint.h>
int8_t
int16_t
int32_t
int64_t
signed integer type with width of
exactly 8, 16, 32 and 64 bits respectively
with no padding bits and using 2's complement for negative values
(provided only if the implementation directly supports the type)
int_fast8_t
int_fast16_t
int_fast32_t
int_fast64_t
fastest signed integer type with width of
at least 8, 16, 32 and 64 bits respectively
int_least8_t
int_least16_t
int_least32_t
int_least64_t
smallest signed integer type with width of
at least 8, 16, 32 and 64 bits respectively
intmax_t maximum width integer type
intptr_t integer type capable of holding a pointer
uint8_t
uint16_t
uint32_t
uint64_t
unsigned integer type with width of
exactly 8, 16, 32 and 64 bits respectively
(provided only if the implementation directly supports the type)
uint_fast8_t
uint_fast16_t
uint_fast32_t
uint_fast64_t
fastest unsigned integer type with width of
at least 8, 16, 32 and 64 bits respectively
uint_least8_t
uint_least16_t
uint_least32_t
uint_least64_t
smallest unsigned integer type with width of
at least 8, 16, 32 and 64 bits respectively
uintmax_t maximum width unsigned integer type
uintptr_t unsigned integer type capable of holding a pointer

[edit] Macro constants

Defined in header <stdint.h>
Signed integers : minimum value
INT8_MININT16_MININT32_MININT64_MIN
minimum value of an object of type int8_t, int16_t, int32_t, int64_t
(macro constant)
INT_FAST8_MININT_FAST16_MININT_FAST32_MININT_FAST64_MIN
minimum value of an object of type int_fast8_t, int_fast16_t, int_fast32_t, int_fast64_t
(macro constant)
INT_LEAST8_MININT_LEAST16_MININT_LEAST32_MININT_LEAST64_MIN
minimum value of an object of type int_least8_t, int_least16_t, int_least32_t, int_least64_t
(macro constant)
INTPTR_MIN
minimum value of an object of type intptr_t
(macro constant)
INTMAX_MIN
minimum value of an object of type intmax_t
(macro constant)
Signed integers : maximum value
INT8_MAXINT16_MAXINT32_MAXINT64_MAX
maximum value of an object of type int8_t, int16_t, int32_t, int64_t
(macro constant)
INT_FAST8_MAXINT_FAST16_MAXINT_FAST32_MAXINT_FAST64_MAX
maximum value of an object of type int_fast8_t, int_fast16_t, int_fast32_t, int_fast64_t
(macro constant)
INT_LEAST8_MAXINT_LEAST16_MAXINT_LEAST32_MAXINT_LEAST64_MAX
maximum value of an object of type int_least8_t, int_least16_t, int_least32_t, int_least64_t
(macro constant)
INTPTR_MAX
maximum value of an object of type intptr_t
(macro constant)
INTMAX_MAX
maximum value of an object of type intmax_t
(macro constant)
Unsigned integers : maximum value
UINT8_MAXUINT16_MAXUINT32_MAXUINT64_MAX
maximum value of an object of type uint8_t, uint16_t, uint32_t, uint64_t
(macro constant)
UINT_FAST8_MAXUINT_FAST16_MAXUINT_FAST32_MAXUINT_FAST64_MAX
maximum value of an object of type uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t
(macro constant)
UINT_LEAST8_MAXUINT_LEAST16_MAXUINT_LEAST32_MAXUINT_LEAST64_MAX
maximum value of an object of type uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t
(macro constant)
UINTPTR_MAX
maximum value of an object of type uintptr_t
(macro constant)
UINTMAX_MAX
maximum value of an object of type uintmax_t
(macro constant)

[edit] Function macros for minimum-width integer constants

INT8_CINT16_CINT32_CINT64_C
expands to an integer constant expression having the value specified by its argument and the type int_least8_t, int_least16_t, int_least32_t, int_least64_t respectively
(function macro)
INTMAX_C
expands to an integer constant expression having the value specified by its argument and the type intmax_t
(function macro)
UINT8_CUINT16_CUINT32_CUINT64_C
expands to an integer constant expression having the value specified by its argument and the type uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t respectively
(function macro)
UINTMAX_C
expands to an integer constant expression having the value specified by its argument and the type uintmax_t
(function macro)
#include <stdint.h>
UINT64_C(0x123) // might expand to 0x123ULL or 0x123UL


[edit] Format macro constants

Defined in header <inttypes.h>
Format constants for the fprintf family of functions
PRId8PRId16PRId32PRId64PRIdLEAST8PRIdLEAST16PRIdLEAST32PRIdLEAST64PRIdFAST8PRIdFAST16PRIdFAST32PRIdFAST64PRIdMAXPRIdPTR
format conversion specifier to output a signed decimal integer value of type int8_t, int16_t, int32_t, int64_t, int_least8_t, int_least16_t, int_least32_t, int_least64_t, int_fast8_t, int_fast16_t, int_fast32_t, int_fast64_t, intmax_t, intptr_t respectively, equivalent to %d for int
(macro constant)
PRIi8PRIi16PRIi32PRIi64PRIiLEAST8PRIiLEAST16PRIiLEAST32PRIiLEAST64PRIiFAST8PRIiFAST16PRIiFAST32PRIiFAST64PRIiMAXPRIiPTR
format conversion specifier to output a signed decimal integer value of type int8_t, int16_t, int32_t, int64_t, int_least8_t, int_least16_t, int_least32_t, int_least64_t, int_fast8_t, int_fast16_t, int_fast32_t, int_fast64_t, intmax_t, intptr_t respectively, equivalent to %i for int
(macro constant)
PRIu8PRIu16PRIu32PRIu64PRIuLEAST8PRIuLEAST16PRIuLEAST32PRIuLEAST64PRIuFAST8PRIuFAST16PRIuFAST32PRIuFAST64PRIuMAXPRIuPTR
format conversion specifier to output an unsigned decimal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to %u for unsigned int
(macro constant)
PRIo8PRIo16PRIo32PRIo64PRIoLEAST8PRIoLEAST16PRIoLEAST32PRIoLEAST64PRIoFAST8PRIoFAST16PRIoFAST32PRIoFAST64PRIoMAXPRIoPTR
format conversion specifier to output an unsigned octal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to %o for unsigned int
(macro constant)
PRIx8PRIx16PRIx32PRIx64PRIxLEAST8PRIxLEAST16PRIxLEAST32PRIxLEAST64PRIxFAST8PRIxFAST16PRIxFAST32PRIxFAST64PRIxMAXPRIxPTR
format conversion specifier to output an unsigned hexadecimal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to %x for unsigned int
(macro constant)
PRIX8PRIX16PRIX32PRIX64PRIXLEAST8PRIXLEAST16PRIXLEAST32PRIXLEAST64PRIXFAST8PRIXFAST16PRIXFAST32PRIXFAST64PRIXMAXPRIXPTR
format conversion specifier to output an unsigned uppercase hexadecimal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to %X for unsigned int
(macro constant)
Format constants for the fscanf family of functions
SCNd8SCNd16SCNd32SCNd64SCNdLEAST8SCNdLEAST16SCNdLEAST32SCNdLEAST64SCNdFAST8SCNdFAST16SCNdFAST32SCNdFAST64SCNdMAXSCNdPTR
format conversion specifier to input a signed decimal integer value of type int8_t, int16_t, int32_t, int64_t, int_least8_t, int_least16_t, int_least32_t, int_least64_t, int_fast8_t, int_fast16_t, int_fast32_t, int_fast64_t, intmax_t, intptr_t respectively, equivalent to %d for int
(macro constant)
SCNi8SCNi16SCNi32SCNi64SCNiLEAST8SCNiLEAST16SCNiLEAST32SCNiLEAST64SCNiFAST8SCNiFAST16SCNiFAST32SCNiFAST64SCNiMAXSCNiPTR
format conversion specifier to input a signed decimal/octal/hexadecimal integer value of type int8_t, int16_t, int32_t, int64_t, int_least8_t, int_least16_t, int_least32_t, int_least64_t, int_fast8_t, int_fast16_t, int_fast32_t, int_fast64_t, intmax_t, intptr_t respectively, equivalent to %i for int
(macro constant)
SCNu8SCNu16SCNu32SCNu64SCNuLEAST8SCNuLEAST16SCNuLEAST32SCNuLEAST64SCNuFAST8SCNuFAST16SCNuFAST32SCNuFAST64SCNuMAXSCNuPTR
format conversion specifier to input an unsigned decimal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to %u for unsigned int
(macro constant)
SCNo8SCNo16SCNo32SCNo64SCNoLEAST8SCNoLEAST16SCNoLEAST32SCNoLEAST64SCNoFAST8SCNoFAST16SCNoFAST32SCNoFAST64SCNoMAXSCNoPTR
format conversion specifier to input an unsigned octal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to %o for unsigned int
(macro constant)
SCNx8SCNx16SCNx32SCNx64SCNxLEAST8SCNxLEAST16SCNxLEAST32SCNxLEAST64SCNxFAST8SCNxFAST16SCNxFAST32SCNxFAST64SCNxMAXSCNxPTR
format conversion specifier to input an unsigned hexadecimal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to %x for unsigned int
(macro constant)
SCNX8SCNX16SCNX32SCNX64SCNXLEAST8SCNXLEAST16SCNXLEAST32SCNXLEAST64SCNXFAST8SCNXFAST16SCNXFAST32SCNXFAST64SCNXMAXSCNXPTR
format conversion specifier to input an unsigned uppercase hexadecimal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to %X for unsigned int
(macro constant)

[edit] Example

#include <stdio.h>
#include <inttypes.h>
 
int main(void)
{
    printf("%zu\n", sizeof(int64_t));
    printf("%s\n", PRId64);
    printf("%+"PRId64"\n", INT64_MIN);
    printf("%+"PRId64"\n", INT64_MAX);
 
    int64_t n = 7;
    printf("%+"PRId64"\n", n);
 
    return 0;
}

Possible output:

8
ld
-9223372036854775808
+9223372036854775807
+7

[edit] See also